click for previous page TETRAG 1983 FAO SPECIES IDENTIFICATION SHEETS FISHING AREA 51 (W. Indian Ocean) TETRAGONURIDAE Squaretails Body very elongate, cylindrical; caudal peduncle, very long and thick, square in cross-section, with modified scales forming 2 lateral keels on each side near base of caudal fin. Head long and somewhat broad, snout long and blunt; eyes large, without adipose tissue and with a series of grooves on posterior rim; mouth fairly large, maxilla extending to below eye; premaxilla not protractile; only the ventral border of maxilla visible below large lacrimal bone, lower jaw appears to shut within upper; teeth small, pointed and recurved in upper jaw; large, flattened and knife-like in lower jaw; opercles fleshy. Two dorsal fins, the first originating over tip of pectoral fin, with 10 to 20 short spines which fold into a groove, the second with a much shorter base, with 10 to 17 rays; a single anal fin, similar to the second dorsal; pectoral fins small and rounded; pelvics very small, inserted behind pectoral fin bases and anterior to origin of first dorsal; caudal fin with 2 rounded lobes, not strongly forked. Lateral line without pored scales, slightly arched anteriorly, then descending to run along mid-line of sides and ending on caudal peduncle. Scales moderate in size, with heavy keels, very adherent and following a geodesic pattern around the body; top of head and snout naked, with small pores. Colour: adults uniformly brown, ranging from tan to almost black, the young often greyish. Squaretails are rather small-sized oceanic epi- or mesopelagic fishes (up to about 30 cm in length), almost never seen inshore. They feed on soft-bodied pelagic invertebrates, and the young commonly occur in association with salps, even living within them. There are reports that the flesh may be poisonous, and they can in no case be considered to have fishery potential. Squaretails do figure in the diets of large oceanic fishes. long D1 strong scales in short D2 geodesic pattern keels box-like mouth - 2 - FAO Sheets TETRAGONURIDAE Fishing Area 51 SIMILAR FAMILIES OCCURRING IN THE AREA : Nomeidae: body compressed, generally with elongate pectoral fins; mouth small; scales thin, small, and easily shed; no keels on caudal peduncle; caudal fin lobes often folded. mouth caudal fin lobes small wing-like often folded pectoral fin Nomeidae (Cubiceps) GENERA OCCURRING IN THE AREA: A single genus, Tetragonurus. LIST OF SPECIES OCCURRING IN THE AREA: Tetragonurus atlanticus Lowe, 1839 Tetragonurus pacificus Abe, 1953 Prepared by R.L. Haedrich, Memorial University of Newfoundland, St. John's, Newfoundland, Canada TETRAO 1983 FAO SPECIES IDENTIFICATION SHEETS FISHING AREA 51 (W. Indian Ocean) TETRAODONTIDAE (including Canthigasteridae) Pufferfishes, blowfishes, tobies Small to moderate-sized fishes (up to 75 cm in length) with a heavy, blunt body capable of rapid inflation by intake of water (or air). Head large and blunt, jaws modified to form a beak of 4 heavy, powerful teeth, 2 above and 2 below; gill openings simple slits anterior to pectoral fins; eyes located high on head. Pelvic fins absent; dorsal and anal fins located far posteriorly, containing no spines, but 7 to 15 soft rays; caudal fin truncate, rounded, or emarginate to somewhat lunate. Lateral lines, when present often indistinct, forming an interconnecting pattern on the sides of head and body, but quite distinct in some genera, e.g., Fugu and Torquigener. Typical scales absent, but numerous small spiny prickles often present on back and/or belly, sometimes on sides. Colour: most species are mottled and variegated on back and sides, sometimes with spots of various sizes and colours, while others are of plain coloration. Pufferfishes are inhabitants of tropical and temperate seas, most frequent in shallow inshore waters, sometimes entering brackish and fresh waters, but a few species are pelagic. Usually found alone, although some species school together, especially for mating purposes. They have the ability to inflate themselves with either air or water as a deterrent to predators. In addition, the viscera and skin of most species are poisonous, some more than others. However, the effect of this poison on other marine animals is not fully understood, whereas its toxicity to terrestrial animals is well known. Careful preparation is required to render pufferfish flesh safe to eat (removal of skin and viscera) and the resultant product is considered a delicacy in some countries (e.g., Fugu in Japan). Nevertheless, many deaths still occur each year from the consumption of these fishes. gill opening beak deflated inflated pelvic fins absent - 2 - FAO Sheets TETRAODONTIDAE Fishing Area 51 SIMILAR FAMILIES OCCURRING IN THE AREA: Diodontidae: strong elongate spines cover head and body; a single tooth in each of the upper and lower jaws (2 teeth in each jaw in Tetraodontidae). Monacanthidae: spinous dorsal fin present, usually consisting of one strong spine with a second much smaller spine at its rear base. Diodontidae first dorsal fin spine second dorsal fin spine very small Diodontidae Tetraodontidae tooth plates keel Monacanthidae KEY TO GENERA OCCURRING IN THE AREA: 1a. Nostrils minute, rarely visible without aid of Canthigaster Fig.1 magnification; dorsal surface posterior to eyes distinctly keeled (Fig.1) ............................... Canthigaster 1b. Nostrils easily visible without magnification; dorsal surface posterior to eyes more or less smooth, without a distinct keel 2a. Nostril an upright sac with 2 openings (Fig.2a) a) Lagocephalus b) Chelonodon c) Arothron 3a. A single lateral line on side of body nostril Fig.2 (Fig.3) ............................................. Sphoeroides 1 lateral line 3b. Two lateral lines on side of body (Figs 4 and 5) Sphoeroides Fig.3 - 3 - FAO Sheets TETRAODONTIDAE Fishing Area 51 upper lateral line 4a. Caudal fin lunate to emarginate (Fig.4) ....................................... Lagocephalus skin fold 4b. Caudal fin rounded or truncate (Fig.5) 5a. bony interorbital region broad lower lateral line Lagocephalus Fig.4 6a. No raised skinfold along lower side of body, or if present, mouth antero- skin fold dorsally positioned .... Amolyrhynchotes 6b. A raised skinfold along lower side of body; mouth anteriorly positioned ................... Fugu Torquigener Fig.5 5b. bony interorbital region narrow ..Torquigener 2b. Nostril either an upraised cup with 2 fleshy lobes (Fig.2b) or a solid bifid ten- tacle (Fig.2c) 7a. A single lateral line on side of body (Fig.7) …...... Arothron Amblyrhynchotes Fig.6 7b. Two lateral lines, the upper joining the lower in the region above or behind the anal fin (Fig.8) 8a. back and belly with spines .......... Chelonodon Arothron Fig.7 8b. belly only with spines .......... Chelonodontops Chelonodon Fig.8 - 4 - FAO Sheets TETRAODONTIDAE Fishing Area 51 LIST OF SPECIES OCCURRING IN THE AREA: Amblyrhynchotes honckenii (Bloch, 1796) Amblyrhynchotes spinosissimus (Regan, 1908) Arothron hispidus (Lacepéde, 1802) Arothron immaculatus (Bloch & Schneider, 1801) Arothron inconditus Smith, 1958 Arothron leopardus (Day, 1878) Arothron mapp (Lesson, 1830) Arothron meleagris (Lacepéde, 1798) Arothron nigropunctatus (Bloch & Schneider, 1801) Arothron stellatus Bloch & Schneider, 1801) Canthigaster amboinensis (Bleeker, 1865) Canthigaster bennetti (Bleeker, 1854) Canthigaster coronata (Vaillant & Sauvage, 1875) Canthigaster janthinuroptera (Bleeker, 1855) Canthigaster margaritata (Rüppell, 1828) Canthigaster natalensis (Günther, 1870) Canthigaster pygmaea Allen & Randall, 1977 Canthigaster rivulata (Schlegel, 1850) Canthigaster smithae Allen & Randall, 1977 Canthigaster solandri (Richardson, 1844) Canthigaster tyleri Allen & Randall, 1977 Canthigaster valentini (Bleeker, 1853) Chelonodon fluviatilis (Buchanan, 1822) Chelonodon laticeps Smith, 1947 Chelonodon patoca (Buchanan, 1822) Chelonodontops pulchellus Smith, 1958 Fugu oblongus (Bloch, 1786) Lagocephalus inermis (Temminck & Schlegel, 1844) Lagocephalus lagocephalus Linnaeus,1758 Lagocephalus lunaris (Bloch & Schneider, 1801) Lagocephalus sceleratus (Gmelin, 1789) Lagocephalus spadiceus (Richardson,1844) Sphoeroides pachygaster (Müller & Troschel,1848) Sphoeroides pleurospilus (Regan, 1919) Torquigener hypselogeneion (Bleeker, 1852) Prepared by G. Hardy, National Museum of New Zealand, Wellington, New Zealand and B. Hutchins, Western Australian Museum, Perth, Australia TOX 1983 FAO SPECIES IDENTIFICATION SHEETS FISHING AREA 51 (W. Indian Ocean) TOXOTIDAE Archerfishes, riflefishes Body laterally compressed. Eye large; mouth moderate in size. A single dorsal fin with 4 or 5 spines and 12 to 14 rays; anal fin with 3 spines and 15 to 17 rays. Head and body covered with small to moderate scales. Colour: usually whitish or silvery with several dark spots or bars on sides. Relatively small fishes living individually or in small groups in brackish (sometimes only slightly) water or in freshwater streams. They are frequently seen near the surface and are reknowned for their ability to knock down insects from overhanging vegetation with a jet of water squirted from the mouth. - 2 - FAO Sheets TOXOTIDAE Fishing Area 51 SIMILAR FAMILIES OCCURRING IN THE AREA: Pempheridae: dorsal fin relatively short, placed above pectoral fin; anal fin long, usually with more than 30 rays (17 or less in Toxotidae). Bathyclupeidae: dorsal fin spines absents anal fin long with a single spine and more than 20 rays; body Pempheridae elongate (depth 3 or 4 times in standard length); fragile